The present invention relates to an X-ray imaging system which irradiates an object with X-rays, and detects X-rays transmitted through the object to obtain transmission X-ray data, thereby forming a visible image based on the transmission X-ray data and, more particularly, to a scattered X-ray elimination technique suitable for a so-called digital radiography apparatus which converts an X-ray image into digital data.
In conventional X-ray imaging systems, a detector for detecting X-rays receives direct X-rays transmitted through an object without being scattered, as well as scattered X-rays scattered by the object. The scattered X-rays are a major factor contributing to the degradation of contrast and sharpness of an X-ray image obtained through the detector. For this reason, in X-ray imaging systems, it is very important to eliminate scattered X-rays.
In order to eliminate scattered X-rays, a grid is usually used in conventional systems. However, since the grid itself generates scattered X-rays, it cannot perform satisfactory elimination of scattered X-rays.
If scattered X-rays can be eliminated, a contrast and sharpness of an X-ray image can be improved, thus providing a good X-ray image. In addition, if an image based on direct X-rays can be obtained, attenuation of the X-rays by the object can be accurately calculated by logarithmic conversion of the image data. Therefore, it is very desirable to eliminate scattered X-rays.
Although various studies have been made on the nature of these scattered X-rays, since X-ray scattering involves complicated phenomena, many aspects thereof still remain unsolved.